There are various types of miniaturized micro-electromechanical systems (MEMS) devices, including MEMS resonator devices, which transpose properties of mechanical resonance in the electrical domain. Potential applications of MEMS resonator devices include electrical signal processing (e.g. filtering, providing time references, etc.) and vibrating sensors (e.g., inertial sensors, mass detectors, label free detectors, pressure sensors, force sensors, etc.), for example. MEMS resonator devices used as vibrating sensors may be incorporated into atomic force microscopy (AFM) applications.
Various physical principles may be used to assure electromechanical transduction performed by the MEMS resonator devices. For example, capacitive transducers are widely employed because they are easily integrated with the mechanical part, and have well established fabrication processes compatible with semiconductor integrated circuit technologies. However, capacitive transducers generally have two drawbacks, as transducers are downsized to reach higher resonance frequencies. First, capacitive transducers present electrical impedance that significantly exceeds the 50-ohm standard. Second, capacitive transducers have parasitic input/output coupling capacitance. Therefore, the measured signal from a capacitive transducer is generally weak and superimposed on a parasitic signal floor, which may mask the desired mechanical resonance signal. The high impedance value (e.g., several kilo-ohm) presented by the MEMS resonator devices to the measurement set-up, typically a vector network analyzer, negates much of the benefit that would be otherwise attained from optimal sensitivity and measurement dynamic. Therefore, electrical characterizations of the MEMS resonator devices exhibit particularly poor signal-to-noise ratios.